Ahhh...The old cant get the damper rod out ..havn't we all had that one more than once in a lifetime
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Mate this may help , I dont have access to a rattle gun so I improvised this .. it's worked a real treat.
Take a tent pole 2cm OD approx. , take a disused socket ( I used an old 1/2 inch ) of 1.5 cm.OD
Take a klingon flux laser gun (or a hacksaw) and cut two sides out of the socket so that it fits over the flat sides of the top of the damper rod ( I have a TM 125 I assume the 250 would be the same ) also drill a hole in the top of the pole so you can insert a screwdriver to assist in stopping the pole from turning when you are undoing the bottom screw.
Now take a precision instrument (like a hammer , I have one of these instead of a rattle gun) and gently bash the crap out of it and fit the socket snuggly into the bottom of the tent pole.
Insert tent pole/socket down fork tube and locate top of rod , hang on tight and use your allen key ( I found using another small dia. long socket /tube to fit over the end of the key will give you some extra leverage as well)